Author Archives: admin

HF Power-Amplifier MRF101

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This blog video discusses the power amp design of the DIY transceiver. A single MRF101 LDMOS RF power Mosfet delivers up to 80W in the 20m, 40m and 80m band.

Preamplifier design and test

You can not drive the power amplifier (MFR101A ) directly with the output of the AD831 mixer. 10dBm power ist not enough. So I did design a 14dB voltage gain amplifier to get the needed power to fully get the final 50W output from the power amp.

Digital filter experiments on STM32F4

Here are some experiments with a simple first IIR filter implemented on a STM32F4. After some theory the design and implementation is presented. Enjoy!

Active filter experiments

We look at the basic concepts of active filters, design a 2nd order lowpass with TI’s filterdesign tool and then build a filter and measure the filter performance on the lab bench. Maybe you want to watch the introduction to electronics filters first, since I do reference to that video so what.

Introduction on electronic filters

This series of videos give you an overview/introduction on electronic filters. basic introduction to electronics filters analog / passiv filters crystal filters active filters digital filters This first video talks about filter specifications, filter types, basic RC filter discussion and shrot discussion on s-parameters. Here you can find more videos about “electronic filters”:

RF mixers

This video discusses theory, active and passive mixers, simulation with LTSpice and GNU radio. Watch the video here:


Dokumentation DIY Transceiver: Types of transceivers Analog bandpassfilter Crystal filters Digital Filters Mixers_1 Mixers_2 Pre-Amplifier Power-Amplifier Documentation Filter Theory & Design: Introduction to electronic filters Active filters Digital Filters Software: Digital Filter IIR on STM32F4 Discovery with PmodI2S2 Transceiver CPU on STM32F735DK with TouchGFX Schematics: Crystal Filter Board Bandpass Board Mic amplifier and two tone […]

Design bandpass and lowpass filter

This is how I did design the bandpass and lowpass filters.

Design a crystal ladder filter

See how I approached the design of a 8 pole crystal ladder filter for SSB @9MHz and with a bandwidth of 2.4 kHz.

Design of the antenna amplifier

Check out how the antenna amplifier got designed, simulated and tested.